1. Field of the Invention
The present invention relates to microwave ovens, and more particularly, to a microwave oven which can heat food more uniformly.
2. Description of the Related Art
In general, the microwave oven (MWO) cooks food using heat from intermolecular friction caused by disturbance of molecular array of the food at direction of a microwave (2,450 MHz) to the food.
The microwave oven is provided with a cavity for heating the food, and a magnetron on one side of the cavity for generating the microwave. The microwave has a particular resonance mode within the cavity. Energy of the microwave is concentrated at a certain part of an inside of the cavity. Therefore, for uniform heating of the food, particular methods are required. The methods are a first method in which food is moved within the cavity, and a second method in which a radiation condition of the microwave is varied.
In the first method, the food moves along an inside of the cavity having a non-uniform microwave energy formed therein. As a typical example of the first method, in a turn table method, a turn table having the food placed thereon is rotated. The circling food is uniformly heated in a circumferential direction. However, a radial direction heating of the food is not uniform.
In the meantime, in the second method, a mode of the microwave directed to an inside of the cavity is varied, for preventing the microwave from keep focused on a part. As typical examples of the second methods, there are methods using a stirrer fan or a rotating antenna. In those methods, an emission condition of the microwave energy to the inside of the cavity through a waveguide is varied, to emit microwave of a variety of modes.
In the meantime, an OTR (Over The Range) type of microwave oven has a hood over the microwave oven. The OTR type of microwave oven is used as a built-in type microwave oven that is built-in kitchen furniture.
Because the kitchen furniture is installed along a wall surface of the room, a size of the kitchen furniture is limited. In general, since the microwave is extended in a lateral direction due to such a limit, the cavity formed therein has a large width, and a depth smaller than the width.
If the turntable is mounted on an inside of the cavity, a radius of the turn table is limited by the depth of the cavity. Therefore, the mounting of the turn table on the OTR type of microwave oven is not desirable in view of utilization of a space. The OTR type of microwave oven is provided with an oblong dish extended in a lateral direction to the inside of the cavity, which is not rotatable.
Accordingly, it is preferable that the dish in the cavity for placing the food thereon makes, not a rotating movement, but linear reciprocating movement. A microwave oven of which dish makes liner reciprocating movement is called as a side by side type microwave oven.
However, the side by side type of microwave oven has the following problems.
The side by side type of microwave oven has very small stroke of liner movement. Therefore, despite of emission of microwaves of a variety of modes to the inside of the cavity, it is liable that the food is heated non-uniformly compared to the turn table.
Moreover, even in a case the stirrer fan is rotated to vary a microwave pattern, it is difficult of solve the problem of the non-uniformity of the heating pattern due to above reason.